Abstract Evolution takes place in an ecological setting that typically involves interactions with... more Abstract Evolution takes place in an ecological setting that typically involves interactions with other organisms. To describe such evolution, a structure is needed which incorporates the simultaneous evolution of interacting species.
Evolutionary consequences of fishing and their implications for salmon
Abstract We review the evidence for fisheries-induced evolution in anadromous salmonids. Salmon a... more Abstract We review the evidence for fisheries-induced evolution in anadromous salmonids. Salmon are exposed to a variety of fishing gears and intensities as immature or maturing individuals. We evaluate the evidence that fishing is causing evolutionary changes to traits including body size, migration timing and age of maturation, and we discuss the implications for fisheries and conservation.
In many populations of plants, reproduction and mortality depend both on age and size. This paper... more In many populations of plants, reproduction and mortality depend both on age and size. This paper develops a model to describe the dynamics of such a population, classifying individual both by age and size. It is based on a model originally proposed by Goodman (1969) as an extension to the Leslie matrix. The model allows a projection of the transient dynamics of a population from an arbitrary set of starting numbers.
Evolution of recombination in populations experiencing frequency-dependent selection with time delay
Abstract This paper proposes a model for the evolution of recombination. The model is based on th... more Abstract This paper proposes a model for the evolution of recombination. The model is based on the notion that when a species (say species 1) interacts with other antagonistic species, species 1 will act as a selective force on them, favouring antagonists best able to destroy its most frequent phenotypes. Only if the progeny of these phenotypes are different from their parents are they able to escape the full force of selected antagonists.
Abstract Four steps through which parasitic intracellular symbionts could bring about the evoluti... more Abstract Four steps through which parasitic intracellular symbionts could bring about the evolution of two sexes are considered. In the first step, a primitive host population has biparental cytoplasmic inheritance and lacks gametic differentiation: parasitic cytoplasmic elements readily invade and spread by vertical transmission through such host populations, even if they have major deleterious effects on their hosts.
Mar Ecol Prog Ser 208: 299–313, 2000 deemed adequate to paint robust caricatures of fish stock he... more Mar Ecol Prog Ser 208: 299–313, 2000 deemed adequate to paint robust caricatures of fish stock health. For example, many stock assessments have been predicated on the assumption that survey estimates of abundance, age-specific metrics of commercial catch, and a broad sense of the geographical limits of a commercially harvested fish population are all that one really requires to understand and predict the effects of fishing on fish populations.
Abstract Species-rich plant communities appear to defy the competitive exclusion principle, showi... more Abstract Species-rich plant communities appear to defy the competitive exclusion principle, showing relatively few obvious niche differences between coexisting species. Here we explore alternatives to the potentially endless search for new niche axes. Spatial aggregation in populations, non-transitive competition, episodes of density-independent mortality and various non-equilibrium theories allow trophically similar species to coexist for extended periods.
Taylor's law and body size in exploited marine ecosystems
Abstract Taylor's law (TL), which states that variance in population density is related to mean d... more Abstract Taylor's law (TL), which states that variance in population density is related to mean density via a power law, and density-mass allometry, which states that mean density is related to body mass via a power law, are two of the most widely observed patterns in ecology. Combining these two laws predicts that the variance in density is related to body mass via a power law (variance-mass allometry). Marine size spectra are known to exhibit density-mass allometry, but variance-mass allometry has not been investigated.
The standard assumption underlying the formulation of models for population dynamics (such as the... more The standard assumption underlying the formulation of models for population dynamics (such as the logistic growth equation, the Lotka–Volterra predator–prey model, and the Kermack and McKendrick epidemiological equations, to name a few) is that populations spread homogeneously through space and that individuals mix rapidly.
Dinosaur skeletons have recently been found well within the contemporary Arctic and Antarctic Cir... more Dinosaur skeletons have recently been found well within the contemporary Arctic and Antarctic Circles. These discoveries have surprised palaeontologists who regarded the dinosaurs as warm-adapted animals.
Ecological drivers of stability and instability in marine ecosystems
Abstract A stability analysis of the steady state of marine ecosystems is described. The study wa... more Abstract A stability analysis of the steady state of marine ecosystems is described. The study was motivated by the approximate invariance of biomass in logarithmic size intervals, which is widely observed in marine ecosystems. This invariance is recovered as the steady state of dynamic models of size spectra, which, unlike traditional species-based models of food webs, explicitly account for the mass gained by an individual organism when it eats a prey item.
It has been argued that mutualisms are non-specific when mutualistic interactions are weak and tr... more It has been argued that mutualisms are non-specific when mutualistic interactions are weak and transient, and berome more specific as interactions increase in strength. However, this runs counter to the observation that there exist tightly linked mutualisms of great antiquity that are highly nonsperific. Here we argue that mutualism generates positive, interspecific, frequency-dependent selection, which acts as a cohesive evolutionary force, discouraging evolution of specificity.
Selective fishing and phenotypic evolution: past, present and future
ABSTRACT There is accumulating evidence for genetic change caused by fishing. Selection different... more ABSTRACT There is accumulating evidence for genetic change caused by fishing. Selection differentials generated by fishing are detectable within year classes in certain major exploited stocks. Breeding experiments in the aquaculture industry demonstrate the existence of genetic variation in production-related traits. Genetic change in growth rates due to fishing has been found in experimental systems. There is evidence that changes in maturation taking place in fish stocks have a genetic component.
The conventional selectivity paradigm is briefly reviewed and its performance examined from an ec... more The conventional selectivity paradigm is briefly reviewed and its performance examined from an ecosystem perspective. It is stressed that the overall (cumulative) selectivity of the harvest process in an ecosystem is the result of nested selection by fishers and fisheries of:(i) habitats;(ii) species assemblages;(iii) populations and (iv) individuals. A range of ecosystem models predict a strong impact of concentrated fishing (selective fishing) on the ecosystem structure stability, resilience and productivity.
The states to which multispecies communities can tend has been an important issue to ecology, but... more The states to which multispecies communities can tend has been an important issue to ecology, but one in which rather little progress has been made at a theoretical level through lack of a tractable global theory of the dynamics. This paper explores the use of a global theory called@'permanence@'that indicates whether the boundary of a phase space is a repellor to orbits in the phase space.
Summary 1 We analyse successional changes in local spatial structure of populations of a dominant... more Summary 1 We analyse successional changes in local spatial structure of populations of a dominant late-successional species (Espeletia schultzii) in the high tropical Andes. 2 Spatial maps of plants of E. schultzii and important features of their environment were recorded at early (year 3) and middle (year 8) stages of succession after agricultural disturbance, and in non-cultivated páramo.
Quantification of neighbourhood‐dependent plant growth by Bayesian hierarchical modelling
Summary 1 The effects of neighbours on the growth of individual plants are fundamental to dynamic... more Summary 1 The effects of neighbours on the growth of individual plants are fundamental to dynamics in plant populations and can be described by means of mathematical functions, so-called competition kernels, in formal spatiotemporal models. Little is known about the form and components such functions should have. 2 We evaluate some properties of kernel functions using data on the growth of Arabidopsis thaliana plants in replicated, even-aged stands of many individuals.
Summary 1 Despite three decades of intensive research on seed predation, rather little is known a... more Summary 1 Despite three decades of intensive research on seed predation, rather little is known about how important a role it plays in plant demography. Here a balance sheet of seed predation is drawn up for Pinus sylvestris, based on mortality caused by its main seed predators. This species is of special interest because trees carry seeds throughout the year and can therefore support specialist as well as generalist seed predators.
Summary 1. Successional changes during sequential assembly of food webs were examined. This was c... more Summary 1. Successional changes during sequential assembly of food webs were examined. This was carried out by numerical methods, drawing one species at a time from a species pool and obtaining the permanent (persistent) community emerging at each step. Interactions among species were based on some simple rules about body sizes of consumers and their prey, and community dynamics were described in terms of flows of biomass density. 2.
Summary 1. Species' abundance scales approximately as an inverse power of body mass. This propert... more Summary 1. Species' abundance scales approximately as an inverse power of body mass. This property has been explained on the basis of metabolic rates of organisms of different sizes. 2. This paper considers the additional effect of population dynamics on the abundance–body size relationship, on the grounds that mass flow through food webs also depends on interactions between predators and their prey.
Abstract Evolution takes place in an ecological setting that typically involves interactions with... more Abstract Evolution takes place in an ecological setting that typically involves interactions with other organisms. To describe such evolution, a structure is needed which incorporates the simultaneous evolution of interacting species.
Evolutionary consequences of fishing and their implications for salmon
Abstract We review the evidence for fisheries-induced evolution in anadromous salmonids. Salmon a... more Abstract We review the evidence for fisheries-induced evolution in anadromous salmonids. Salmon are exposed to a variety of fishing gears and intensities as immature or maturing individuals. We evaluate the evidence that fishing is causing evolutionary changes to traits including body size, migration timing and age of maturation, and we discuss the implications for fisheries and conservation.
In many populations of plants, reproduction and mortality depend both on age and size. This paper... more In many populations of plants, reproduction and mortality depend both on age and size. This paper develops a model to describe the dynamics of such a population, classifying individual both by age and size. It is based on a model originally proposed by Goodman (1969) as an extension to the Leslie matrix. The model allows a projection of the transient dynamics of a population from an arbitrary set of starting numbers.
Evolution of recombination in populations experiencing frequency-dependent selection with time delay
Abstract This paper proposes a model for the evolution of recombination. The model is based on th... more Abstract This paper proposes a model for the evolution of recombination. The model is based on the notion that when a species (say species 1) interacts with other antagonistic species, species 1 will act as a selective force on them, favouring antagonists best able to destroy its most frequent phenotypes. Only if the progeny of these phenotypes are different from their parents are they able to escape the full force of selected antagonists.
Abstract Four steps through which parasitic intracellular symbionts could bring about the evoluti... more Abstract Four steps through which parasitic intracellular symbionts could bring about the evolution of two sexes are considered. In the first step, a primitive host population has biparental cytoplasmic inheritance and lacks gametic differentiation: parasitic cytoplasmic elements readily invade and spread by vertical transmission through such host populations, even if they have major deleterious effects on their hosts.
Mar Ecol Prog Ser 208: 299–313, 2000 deemed adequate to paint robust caricatures of fish stock he... more Mar Ecol Prog Ser 208: 299–313, 2000 deemed adequate to paint robust caricatures of fish stock health. For example, many stock assessments have been predicated on the assumption that survey estimates of abundance, age-specific metrics of commercial catch, and a broad sense of the geographical limits of a commercially harvested fish population are all that one really requires to understand and predict the effects of fishing on fish populations.
Abstract Species-rich plant communities appear to defy the competitive exclusion principle, showi... more Abstract Species-rich plant communities appear to defy the competitive exclusion principle, showing relatively few obvious niche differences between coexisting species. Here we explore alternatives to the potentially endless search for new niche axes. Spatial aggregation in populations, non-transitive competition, episodes of density-independent mortality and various non-equilibrium theories allow trophically similar species to coexist for extended periods.
Taylor's law and body size in exploited marine ecosystems
Abstract Taylor's law (TL), which states that variance in population density is related to mean d... more Abstract Taylor's law (TL), which states that variance in population density is related to mean density via a power law, and density-mass allometry, which states that mean density is related to body mass via a power law, are two of the most widely observed patterns in ecology. Combining these two laws predicts that the variance in density is related to body mass via a power law (variance-mass allometry). Marine size spectra are known to exhibit density-mass allometry, but variance-mass allometry has not been investigated.
The standard assumption underlying the formulation of models for population dynamics (such as the... more The standard assumption underlying the formulation of models for population dynamics (such as the logistic growth equation, the Lotka–Volterra predator–prey model, and the Kermack and McKendrick epidemiological equations, to name a few) is that populations spread homogeneously through space and that individuals mix rapidly.
Dinosaur skeletons have recently been found well within the contemporary Arctic and Antarctic Cir... more Dinosaur skeletons have recently been found well within the contemporary Arctic and Antarctic Circles. These discoveries have surprised palaeontologists who regarded the dinosaurs as warm-adapted animals.
Ecological drivers of stability and instability in marine ecosystems
Abstract A stability analysis of the steady state of marine ecosystems is described. The study wa... more Abstract A stability analysis of the steady state of marine ecosystems is described. The study was motivated by the approximate invariance of biomass in logarithmic size intervals, which is widely observed in marine ecosystems. This invariance is recovered as the steady state of dynamic models of size spectra, which, unlike traditional species-based models of food webs, explicitly account for the mass gained by an individual organism when it eats a prey item.
It has been argued that mutualisms are non-specific when mutualistic interactions are weak and tr... more It has been argued that mutualisms are non-specific when mutualistic interactions are weak and transient, and berome more specific as interactions increase in strength. However, this runs counter to the observation that there exist tightly linked mutualisms of great antiquity that are highly nonsperific. Here we argue that mutualism generates positive, interspecific, frequency-dependent selection, which acts as a cohesive evolutionary force, discouraging evolution of specificity.
Selective fishing and phenotypic evolution: past, present and future
ABSTRACT There is accumulating evidence for genetic change caused by fishing. Selection different... more ABSTRACT There is accumulating evidence for genetic change caused by fishing. Selection differentials generated by fishing are detectable within year classes in certain major exploited stocks. Breeding experiments in the aquaculture industry demonstrate the existence of genetic variation in production-related traits. Genetic change in growth rates due to fishing has been found in experimental systems. There is evidence that changes in maturation taking place in fish stocks have a genetic component.
The conventional selectivity paradigm is briefly reviewed and its performance examined from an ec... more The conventional selectivity paradigm is briefly reviewed and its performance examined from an ecosystem perspective. It is stressed that the overall (cumulative) selectivity of the harvest process in an ecosystem is the result of nested selection by fishers and fisheries of:(i) habitats;(ii) species assemblages;(iii) populations and (iv) individuals. A range of ecosystem models predict a strong impact of concentrated fishing (selective fishing) on the ecosystem structure stability, resilience and productivity.
The states to which multispecies communities can tend has been an important issue to ecology, but... more The states to which multispecies communities can tend has been an important issue to ecology, but one in which rather little progress has been made at a theoretical level through lack of a tractable global theory of the dynamics. This paper explores the use of a global theory called@'permanence@'that indicates whether the boundary of a phase space is a repellor to orbits in the phase space.
Summary 1 We analyse successional changes in local spatial structure of populations of a dominant... more Summary 1 We analyse successional changes in local spatial structure of populations of a dominant late-successional species (Espeletia schultzii) in the high tropical Andes. 2 Spatial maps of plants of E. schultzii and important features of their environment were recorded at early (year 3) and middle (year 8) stages of succession after agricultural disturbance, and in non-cultivated páramo.
Quantification of neighbourhood‐dependent plant growth by Bayesian hierarchical modelling
Summary 1 The effects of neighbours on the growth of individual plants are fundamental to dynamic... more Summary 1 The effects of neighbours on the growth of individual plants are fundamental to dynamics in plant populations and can be described by means of mathematical functions, so-called competition kernels, in formal spatiotemporal models. Little is known about the form and components such functions should have. 2 We evaluate some properties of kernel functions using data on the growth of Arabidopsis thaliana plants in replicated, even-aged stands of many individuals.
Summary 1 Despite three decades of intensive research on seed predation, rather little is known a... more Summary 1 Despite three decades of intensive research on seed predation, rather little is known about how important a role it plays in plant demography. Here a balance sheet of seed predation is drawn up for Pinus sylvestris, based on mortality caused by its main seed predators. This species is of special interest because trees carry seeds throughout the year and can therefore support specialist as well as generalist seed predators.
Summary 1. Successional changes during sequential assembly of food webs were examined. This was c... more Summary 1. Successional changes during sequential assembly of food webs were examined. This was carried out by numerical methods, drawing one species at a time from a species pool and obtaining the permanent (persistent) community emerging at each step. Interactions among species were based on some simple rules about body sizes of consumers and their prey, and community dynamics were described in terms of flows of biomass density. 2.
Summary 1. Species' abundance scales approximately as an inverse power of body mass. This propert... more Summary 1. Species' abundance scales approximately as an inverse power of body mass. This property has been explained on the basis of metabolic rates of organisms of different sizes. 2. This paper considers the additional effect of population dynamics on the abundance–body size relationship, on the grounds that mass flow through food webs also depends on interactions between predators and their prey.
Uploads
Papers by Richard Law